661285406 has 4 divisors (see below), whose sum is σ = 991928112. Its totient is φ = 330642702.

The previous prime is 661285369. The next prime is 661285421. The reversal of 661285406 is 604582166.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 661285406.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165321350 + ... + 165321353.

It is an arithmetic number, because the mean of its divisors is an integer number (247982028).

Almost surely, 2^661285406 is an apocalyptic number.

661285406 is a deficient number, since it is larger than the sum of its proper divisors (330642706).

661285406 is a wasteful number, since it uses less digits than its factorization.

661285406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330642705.

The product of its (nonzero) digits is 69120, while the sum is 38.

The square root of 661285406 is about 25715.4701687525. The cubic root of 661285406 is about 871.2236298468.

The spelling of 661285406 in words is "six hundred sixty-one million, two hundred eighty-five thousand, four hundred six".